Cardiac transplant recipients are routinely managed with two drugs (glucocorticoids (Prednisone) and cyclosporine A) that have significant adverse effects upon the skeleton. The study is designed as a natural history study of the changes in bone mineral density, biochemical markers of bone and mineral metabolism, and incidence of fracture after cardiac transplantation. The protocol is straightforward and includes both a longitudinal study (Protocol A) of newly transplanted patients and a cross-sectional study (Protocol B) of previously transplanted patients. Protocol A patients are evaluated prior to or shortly after transplantation with thoracic and lumbar spine films, bone densitometry of the spine, hip and forearm, and serum and urinary biochemical and hormonal markers of bone and mineral metabolism. The biochemistries are repeated at one month after transplantation and the biochemistries and bone density measurement are repeated at 3,6,12,18,24,30, and 36 months after transplantation. In selected patients, bone biopsies will be performed either within the initial 3 months after transplantation to assess the skeletal effects on concurrent high doses of prednisone and cyclosporine A and elucidate the mechanism of early post-transplant bone loss or during the second post-transplant year to assess the effects of cyclosporine A without the confounding effects of glucocorticoids since a number of patients are withdrawn from glucocorticoids toward the end of the first post-transplant year. All Protocol B patients have undergone an initial evaluation that is the same as that of the Protocol A patients. They are then followed with the same evaluation at yearly intervals as long as they wish to participate